Push the basic implementation discussed over the last few weeks.

The current prototype transforms a sequence in a series of overlapping windows, and passes these windows through a sequence of filters; each filter is passerd the score returned by the previous filter, and it's position in the pipeline; if a filter returns a score lower or higher than predefined thresholds, that score is retuned immediately, without running the next filters.

Filters currently implemented are trivial placeholders (random, C/G content, CpG content).